Jack up kit versus dropping the forks.

[robbo]

I wondered if anyone knew if there's a direct relationship between the height of a jack up kit as opposed to lowering the front through the yokes.For example would a 25mm jack up have the same effect as say dropping the front 5mm. Thanks in advance.

[PieEater]

It would be useful to know why you are asking the question.

For me the best option is a 25mm jack-up kit and having the yoke down the forks by ~15mm. I currently have a 50mm jack-up kit and having the front dropped at all adversely affects the handling. The 50mm kit and the forks at the OEM position gives roughly the same handling as the 25mm kit and a ~15mm drop. You could possibly infer from that that a 25mm Jack-up kit has a similar effect to having the forks dropped by ~15mm but I feel that's far too simplistic.

[F4celess]

It would be useful to know why you are asking the question.

For me the best option is a 25mm jack-up kit and having the yoke down the forks by ~15mm. I currently have a 50mm jack-up kit and having the front dropped at all adversely affects the handling. The 50mm kit and the forks at the OEM position gives roughly the same handling as the 25mm kit and a ~15mm drop. You could possibly infer from that that a 25mm Jack-up kit has a similar effect to having the forks dropped by ~15mm but I feel that's far too simplistic.

Any pics on the 50mm dog bones?  :eek

I'm actually about to fit 40mm ones. I was concerned 25mm would look too subtle, so added an extra 15mm to be on the safe side.  :lol

[Dudeofrude]

I'm considering doing this too but mainly just because my seat is too low. I can flat foot with both feet and even stand up off the seat slightly. Didn't really think about the handling differences it might make ?

[F4celess]

I'm considering doing this too but mainly just because my seat is too low. I can flat foot with both feet and even stand up off the seat slightly. Didn't really think about the handling differences it might make ?

Yes, cosmetics is one reason, plus I'm tall and feel like I'm sitting ONTO a chopper sometimes lol. After putting one leg over and sitting down, feels like my head height has dropped about a foot.

High speed stability is affected apparently, by raising the rear on dogbones (obviously magnified the higher you go)... don't know exactly how that will manifest itself, don't want to be in a situation where it happens either!  :eek

[robbo]

Having read Falcon's post regarding changing his usds back to right way up forks because of Spanish MOT bureaucracy, I noted that he'd dropped the forks through the yokes by 12mm. I currently run a 25mm jack up, but as I have the GYT-R bar lowering risers, the space between the fork top and underside of the handlebars is a bit limited but not impossible to drop the forks through. Just wondered how "radical" the 25mm lift was in comparison to dropping the front 12mm, and if the 25mm only equated to say only a 5mm fork drop, then 50mm dog bones would be the way to go.

[Dustydes]

Ive gone 25mm at back 12mm at front with adjustable dogs. Great mod turns so much better. You sit with weight forward into tank instead of rocking back when hard on throttle so more stable acceleration. Front stays more planted and turns into a corner much much better. Shakes her head a small bit on hard acceleration but never has got frightening even with the full monty.
Go for it its not something that cant be reversed easily or will cost you a fortune.
You can make dogs out of flat bar with a couple of holes in, you don't need to shape, that's the way I went first time after R6 shock.


http://www.yamahafz1oa.com/forum/showthr...=dog+bones

[PieEater]

Any pics on the 50mm dog bones?  :eek

One I took last week, you can see the rear wheel is pretty much on the ground but both stands are still usable though I avoid the side stand where I can, the tail is about waist height (6'3").

[PieEater]

Yes, cosmetics is one reason, plus I'm tall and feel like I'm sitting ONTO a chopper sometimes lol. After putting one leg over and sitting down, feels like my head height has dropped about a foot.

High speed stability is affected apparently, by raising the rear on dogbones (obviously magnified the higher you go)... don't know exactly how that will manifest itself, don't want to be in a situation where it happens either!  :eek

I'm 6'3" with an inside leg of 33" with the 50mm Jack up and my Nitron shock on maximum ride height the bike looks and feels the right size for me, I've never experienced high speed stability issues.

[PieEater]

Having read Falcon's post regarding changing his usds back to right way up forks because of Spanish MOT bureaucracy, I noted that he'd dropped the forks through the yokes by 12mm. I currently run a 25mm jack up, but as I have the GYT-R bar lowering risers, the space between the fork top and underside of the handlebars is a bit limited but not impossible to drop the forks through. Just wondered how "radical" the 25mm lift was in comparison to dropping the front 12mm, and if the 25mm only equated to say only a 5mm fork drop, then 50mm dog bones would be the way to go.

I have the GYT-R risers and Renthal 758's the lack of clearance for dropping the yokes was the main reason I went with the 50mm jack-up kit, the other was I wanted the bike to be taller to fit me better.

[robbo]

I have the GYT-R risers and Renthal 758's the lack of clearance for dropping the yokes was the main reason I went with the 50mm jack-up kit, the other was I wanted the bike to be taller to fit me better.

Does that mean you can't rotate the rear wheel for chain lubing. The sidestand wouldn't be an issue as am already using a lengthened one. Yours certainly looks the business and a great location for the pic. too.

[PieEater]

Does that mean you can't rotate the rear wheel for chain lubing.

I can turn the rear wheel as long as the floor is level otherwise it can catch, bare in mind that I also have the ride height adjuster on my shock set to max height so I don't think it will be an issue.

[robbo]

Ok, thanks for your input and advice.Very helpful :thumbup .

[F4celess]

One I took last week, you can see the rear wheel is pretty much on the ground but both stands are still usable though I avoid the side stand where I can, the tail is about waist height (6'3").

Lovely Harrier!  :lol  ...the Bike is looking sweet as well. Doesn't look "extreme" on 50mm.
Definitely a Tail up look, but not over the top. Very sporty.

After finishing the 40mm Links last night (no mods on the front forks), the rear wheel is on the ground, with the centre stand down.
Infact the bike 'rolls' back onto the centre stand much easier, with less jolt, as the rear wheel stays in contact with the ground.

Riding the bike today, DOES feel lovely around the corners, no nasty surprises, plus under hard acceleration (as was said above) there's less tendency for you to be rocked back on the seat, as you are angled more forward. Legs feel much more natural too now, with the longer reach with the ground.

[5LV]

changing the length of the dog bones also changes the rate of compression of the rear shock. iirc it softens it up if you lengthen them.
so not only do you have to be concerned about ride height, but also spring rate and damping.
dropping the forks just changes the weight distribution and steering qualities.
there's a good reason why firms like k tech, maxton are in business.

[PieEater]

changing the length of the dog bones also changes the rate of compression of the rear shock. iirc it softens it up if you lengthen them.
so not only do you have to be concerned about ride height, but also spring rate and damping.
dropping the forks just changes the weight distribution and steering qualities.
there's a good reason where y firms like k tech, maxton are in business.

You are correct but maybe not in the way you think. A jack-up kit uses shorter dogbones firming up the rear which is highly beneficial if you are still running the weak OEM shock, if you are running a decent aftermarket shock you can adjust it to compensate if necessary.

[Dustydes]

Any changes to geometry of bike and suspension should be checked and adjusted as PieEater said.
I will be going R1 with K Tech soon which will be 35mm lower at front and will be fitting a Hyperpro rear shock instead of the R6 (which is a great mod) so expect a lot of changes to be made.
I also have Gilles so can adjust my leg position.
Next summer I plan on having suspension set up by a pro, for about £50. I think its worth it. 

[Dudeofrude]

there's a good reason why firms like k tech, maxton are in business.

Theres a good reason companies like Yamaha are in business. Afterall they put the stock shock in there in the first place. They spend hundreds of thousands in R&D and have teams of specialists design and set up a motorbike to work exactly as it should.
Then the average joe whos buys it decides it's not good enough and changes parts out for something they deem to be 'better' 

[robbo]

I think that all mass produced bikes and cars are built to a price, and in the case of bikes, suspension and sometimes tyres are both areas where money is saved, unless you're buying something a bit up market that comes with eg ohlins. Stock suspension does it's job but is the area that in most cases can be greatly improved with aftermarket units/parts.

[slappy]

The manufacturers make the bikes to fit a very large one size fits all market, and to be safe. The bike has to suit people of vastly different weights, height, leg length, arm length etc, and all this has to be done within a certain price bracket to ensure sales and profit.